Plugging off bottom hole water under pressure



' formation at that point.

Patented Aug. 15, 1939 1 J .YPLUGGING on BOTTOM HOLE WATER UNDER PRESSURE I Roland E. O'Donnell, Midland 'lex, assignor to Halliburton Oil Well Duncan, Okla.

cementing Company,

Application June 3, 1938, Serial No. 211,490

6 Claims.

This invention relates, to the plugging oil of bottom hole water in oil wells or the like, and more particularly to methods and apparatus for cementing oflf bottom hole water under pressure without loading the well with water or mud.

Ordinarily, in the rotary drilling of oil wells as now practiced, mud or other heavy fluid is circulated in the well. A method has recently been devised, however, in which water or oil is used as the circulating fluid, this water or oil having a hydrostatic head at the bottom of the well which is less than that which exists in the Oil or gas from the formation may thus enter the well while the'drilling operations are carried on and these fluids flowupwardly in the annular space between the drill. pipe and the casing or wall of the well, the dis-" charge or return from the well being controlled by means of a choke or valve. Such a method is described in the patent to Foran et al., No. 2,082,329, granted June 1, 1937, for A method of drilling and simultaneously exploring oil wells and the like.

The present invention relates to methods of and apparatus for cementing wells which are drilled according to the process described in the above mentioned Foran patent or similar processes. In cementing a well drilled by such a process, it would, of course, be possible to substitute mud for the water or oil used after which the well could be cemented in the usual way. It

. is desirable, however, not to do this because the mud would then flow into the pay sand or formation and one of the advantages of the pressure drilling process is that this does not take place.

The main object of the present invention there-- fore is to devise a method for plugging of! a water bearing formation in a well drilled bythe pressure drilling process without loading the drilling fluid with mud.

It is a further object to devise novel apparatus adapted for use in plugging oil. a water bearing formation in a well without loading the fluids in the well with mud.

Other objects and advantages reside in certain novel features of the method and apparatus as will become more apparent from the following description taken in connection with the accompanying drawing, in which:

Figure 1 is a schematic representation of an oil well with apparatus constructed inaccordance with the present invention therein;

collar of Figure 4 with a packer mounted therein.

Referring to the drawing indetail, and first to Figure 1, it will be seen that an oil well is there shown at H, the well being provided with a casing 12 which is cemented in place as illustratedat ll. To illustrate the invention, assume that thewell has been drilled to some point beneath the lower end of the casing as illustrated at I4 and that the portion 14 extends through oil bearing formation which maybe limestone, as illustrated at l5, and into a water bearing sand such as is illustrated at", and that it is now desired to plug of! the water bearing formation IS with cement.

If the portion ll of the well has been drilled in under pressure by the use of oil as circulating 25 fluid, the pressure in the formation 15 may be greater than the hydrostatic head of the column of oil within the casing, andoil and water from the formations l5 and I 6 may be flowing upwardly through the casing and out through a conduit ll,

this flow being carefully controlled by a valve l8, commonly referred to in the fields as a pinch I of! valve. To carry out the invention, tubing I9 is lowered into the well through a blow out preventer or some type of tubing head or packing between the tubing and the casing, this being rather diagrammatically illustrated at 20 in Figure 1. Various known tubing heads may be used for this purpose and the construction is preferably such as to permit collars on the tubing to pass therethrough without fluid leaking past the packing thereof even though subjected to considerable pressure. As shown in Figure 2, the lower joint of the tubing I9 is provided with a special collar l9a, which is provided with a choke member 2| and a steel plug 22. The choke member 2| may be screw threaded within the collar I941 as illustrated.

The lower portion of the choke member 21 is tapered as illustrated and the steel plug 22 is driven therein, effectively preventing the upward flow of fluid through the tubing, while the plug 22 r is in place. Beneath the collar Na, a perforated -buli plug is provided, this bull plug serving as means to catch the steel plug 22 when-it is tubing until it is full.

removed from its seat, as will presently be described.

* Due to the plug 22 in the collar Isa, it will be seen that as the tubing I9 is lowered into the well, it is empty.

As shown in Figure 1, the top of the" tubing ll, after being placed in the wellnnay be connected to the usual circulating swivel 24 which is supported by means of taelrle 25 and which is connected to a pump 21 by means of a hose 26.

With the tubing in the well and connections made as illustrated, hydrated lime water or lime solution is preferably then pumped into the Other liquids could of course be used instead of lime water, but it's use is suggested because it may tend to aid the clarifying agent. If desired, a quantity of aquagel may be mixed with water and pumped into I the well behind the lime water.

It will be under stood that during this portion of the process the well will continue to flow and the lime water or aquagel, if it is employed, will be removed from the annular. space between the tubing and the 'casing as the oil from the formation l5 flows upwardly therethrough.

After the well has been conditioned, as noted above, it is desirable that the valve It be closed for a period of time, say thirty minutes, 'before cement is pumped down into the well. The closing of the valve ll causes the pressure to build up in the formation I5.

After the pressure has built up, the calculated amount of cement necessary to flll the hole in the water bearing formation It is mixed and pumped into the well, followed, of course, by some displacing fluid, such as water, andif necessary subjected to sufllcient pressure to squeeze it some distance into the formation Ii.

The cement maybe followed by an ordinary cement plug such as is shown at 28 in Figure 4 or a special cement plug 29 may be employed. In either case the cement plug will effect a shut off inside the tubing when it strikes the shoulder on the choke member 2|.

Where the special plug 29 is employed, as shown in Figure 3, the opening .or bore of the choke member 2| may be provided with threads or other irregular surfaces and the plug 29 provided with a stud 30 which carries dogs 3| adapted to engage the threads in the bore of the member 2| so that the plug 29 is securely latched to the member 2|. 7

If anjordinary cementing plug such as is shown at 28 in Figure 4 is employed, it will remain seated upon the member 2| as long as the pressure above is greater than the pressure below the plug 2!.

It will be understood that as the cement is forced downwardly within the tubing the valve It will be opened slightly to permit thefluids in the tubing to be displaced.

After the cement has been forced into the formation It, the tubing must be removed from the well to avoid its being cemented in place.

To prevent a body of cement from remaining raised, it is preferable to provide a check valve 32 and passage 33 in the collar lid and choke member 2| as illustrated. The valve 32 opens and permits fluid to flow from the exterior to the interior of the collar I911, to displace the cement as the tubing is raised. 7

As the tubing is pulled out the desired amount of back pressure is held on the blow out preventer or packing by manipulation of the valve I8. If a cementing plug of the type shown in Figure 3 is employed the tubing will be again sealed after the cement has been discharged therefrom andcan be gradually removed from the well. If an ordinary cementing plug is employed, as shown in Figure 4, the tubing can be lifted until the hydrostatic head of the fluid in the tubing which is used to force the cement downwardly is about equal to the formation pressure. At this time the valve I8 is closed a little more, this causing the oil or gas from the formation l5 to lift the fluid in the tubing and the plug 28, thus driving all of the added fluid out of the tubing and carrying the plug to the surface. After the cement plug 28 is removed from the tubing a packer may then be pumped down or lowered into-the tubing and secured therein as shown in Figure 5. Any known type of packing device may be employed for this purpose, the arrangement illustrated including an iron body 34 and provided with suitable slips 36 and a rubber packer 31. Any other known suitable packer may be used for this purpose. After the packer 34 is secured in place the tubing can then be pulled out without any oil flowing upwardly sure is high and even though no mud or other heavy fluid is employed to keep the oil or gas in the formation under control.

While the invention has been described in some detail, it isobvious that various changes maybe made in the arrangement'and construction, as well as in the steps for carrying out the method, without departing from the spirit of the inventlo or the scope of the annexed claims.

I claim:

1. The method of cementing a well under pressure which includes lowering an empty conduit sealed at the bottom into the well, filling the conduit with wash fluid after it is in position, breaking the seal at the bottom of the conduit, circulating the wash fluid downwardly through the conduit and upwardly on the outside thereof while controlling the pressure therein by regulating the amount of fluid discharged from the well, then pumping into the conduit a quantity of cement slurry and a following fluid until the cement reaches the bottom of the conduit, again sealing the conduit at the bottom and removing the conduit from the well.

2. The method of cementing a well which includes lowering an empty conduit, sealed at the bottom, into the well, breaking the seal, pumping cement slurry through the conduit, again sealing the conduit at the bottom and removing the conduit from the welll 3. The method of placing a liquid in a certain formation at or near the bottom of a well full of .70

fluid while maintaining more than atmospheric pressure on said fluid which includes placing a in the bull plug 23, as the tubingis initially the liquid to be placed down through the con- 75 duit to displace some of the fluid in the well and maintaining pressure on the liquid and fluid during the placing operation by restricting the discharge of fluid from the well.

4. The method of plugging back a well with cement while maintaining pressure on the fluid therein, which includes placing a sealed conduit in the well, breaking the seal in the conduit after the conduit is in place, pumping cement slurry downwardly through the conduit to displace some of the fluid in the well, maintaining pressure on the slurry and fluid in the well during the displacing operation by restricting the discharge of fluid from the well, again sealing the conduit and removing it from the well.

5. The method of plugging back a well with cement while maintaining pressure on the fluid therein, which includes lowering a conduit, sealed at or near the bottom, into the well, filling the conduit above the seal with a wash liquid, exerting pump pressure upon the wash liquid to break the seal in the conduit and cause the wash liquid to circulate downwardly through said conduit and upwardly on the outside thereof, mixing and pumping into the conduit the calculated amount of cement slurry to fill the desired portion of said well, pumping into the conduit a following fluid until the slurry has left the conduit and again sealing the conduit and removing it from the well, the pressure on the fluid in the well bein maintained at all times during the aforesaid steps by restricting the discharge of fluid from the well.

6. Apparatus adapted for use in cementing a well under pressure including a conduit adapted to be connected to tubing or other conduit means to be lowered into a well, said conduit having a choke member therein, said choke member having a tapered seat in the lower portion thereof, a tapered plug tightly fitted within said seat, said conduit and said choke member also having a passageway from the exterior thereof to the interior at a point beneath said choke member and a check valve in said passageway for permitting fluid to flow only from the exterior to the interior thereof.

ROLAND E. ODONNELL. 

